This invention relates to a method and means for controlling a torque amplifier.
Many present farm tractors include a torque amplifier assembly which is located between the main engine clutch and the transmission of the tractor. The torque amplifier permits the operator to engage a torque amplifier gear when a desired increase in torque is required. The increase in torque can be accomplished with the torque amplifier without disengaging the clutch or shifting the gears in the transmission.
The torque amplifier assembly includes a first shaft which is coupled to the engine output shaft by means of the main clutch. The first shaft includes a torque amplifier gear and a direct drive gear thereon. These gears interlock with complimentary gears on a second shaft which in turn is connected to the transmission of the vehicle.
A direct drive clutch and a torque amplifier clutch are connected to the first shaft. The torque amplifier clutch can be activated to cause rotation to be imparted from the first shaft to the direct drive gear, and the torque amplifier clutch can be actuated to transfer rotation from the first shaft to the torque amplifier gear.
The torque amplifier clutch and the direct drive clutch of prior art systems are connected to hydraulic circuitry which permits the hydraulic pressure to be directed either to the direct drive clutch or the torque amplifier clutch. A switch or valve permits the hydraulic circuitry to be changed so as to transfer the hydraulic pressure to either the direct drive clutch or the torque amplifier clutch.
A problem is encountered with present torque amplifier assemblies whenever the operator changes from the direct drive mode to the torque amplifier mode or whenever the operator changes from the torque amplifier mode back to the direct drive mode. During this transfer there is usually a lurch in the drive train of the tractor resulting from the momentary deactuation of both of the direct drive and the torque amplifier clutches. For example, when the operator switches from the direct drive to the torque amplifier mode, the direct drive clutch is immediately disengaged before the torque amplifier clutch becomes fully engaged. This is because there is a short period of time required for hydraulic pressure to build within the torque amplifier clutch from 0 psi to the amount of pressure required to activate the torque amplifier clutch. When the torque amplifier clutch finally engages, there is a jerk or lurch in the transmission.
Therefore, a primary object of the present invention is the provision of an improved method and means for controlling the torque amplifier.
A further object of the present invention is the provision of an improved method and means for controlling the torque amplifier wherein both the torque amplifier clutch and the direct drive clutch are simultaneously actuated for a short period of time during transfer from one clutch to the other until such time as hydraulic pressure has built up in the transferee clutch at which time the transferor clutch is deactuated.
A further object of the present invention is the provision of a control system for a torque amplifier which can be easily mounted upon existing torque amplifier systems.
A further object of the present invention is the provision of an improved method and means for controlling torque amplifiers which is efficient in operation, simple in construction, and durable and reliable in use.